Rinse aid compositions designed for use in automatic dishwasher machines are well known. These compositions are added during the rinsing cycle of the machine, separately from the detergent composition employed in the main wash cycle(s). The ability to enhance rinsing, and in particular the ability to prevent spot and film formation are common measures of rinse aid performance.
Rinse aid compositions typically contain components such as nonionic surfactants and/or hydrotropes which aid the wetting of the items in the rinse, thereby improving the efficacy of the rinsing process. These surfactants, and rinse aid compositions in general, are not designed for the achievement of a primary soil removal purpose.
The Applicants have found that certain resistant soils/stains, especially bleachable soils/stains, most especially tea stains, can remain on tableware, especially chinaware at the end of the wash cycle of an automatic dishwashing machine.
The Applicants have also found that said resistant soils/stains, especially tea stains on chinaware, may `recolourise` under the conditions of the rinse, thereby enhancing the colour of the soils/stains.
The Applicants have found that the inclusion of certain chelants having disuccinic or diglutaric acid components into said rinse aid formulation enhances the removal of said resistant soils/stains from the tableware during the rinse cycle. The problem of stain recolourisation is thus also avoided. The removal of tea stains from chinaware is particularly enhanced.
The Applicants have also found that the inclusion of said chelants having disuccinic acid or diglutaric acid components into the rinse aid formulations reduces the propensity for the leaching out of any silicious material constituents of the articles in the wash. Hence improved china and glassware properties are provided.